Shoulder Internal Rotator muscles

Authors

Affiliations

Nate Yomogida, PT, DPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, PT, DPT

Doctor of Physical Therapy

B.A. in Neuroscience

Table 1: Glenohumeral Internal Rotator muscles

Muscle	Origin	Insertion	Innervation	Action
Anterior deltoid	Lateral third of clavicle	Deltoid tuberosity of humerus	Axillary n. C5 - C6	GHJ: Flexion, IR, Adduction
Biceps brachii Long head	Supraglenoid tubercle of scapula Adjacent rim of Glenoid Labrum	Radial tuberosity Bicipital aponeurosis	Musculocutaneous n. C5 - C6	Elbow: Flexion, Supination GHJ: Flexion, Stabilization of humeral head during deltoid contraction, Abduction, IR
Biceps brachii Short head	Coracoid process	Radial tuberosity Bicipital aponeurosis	Musculocutaneous n. C5 - C6	Elbow: Flexion, Supination GHJ: Flexion, Stabilization of humeral head during deltoid contraction, Abduction, IR
Coracobrachialis	Coracoid process	Humerus (in line with crest of lesser tubercle)	Musculocutaneous n. C5 - C7	GHJ: Flexion, Adduction, IR
Latissimus dorsi	T7-T12 SP Thoracolumbar fascia Inferior angle of scapula 9-12 ribs Posterior third of Iliac crest	Floor of the intertubercular groove of the humerus	Thoracodorsal n. C6 - C8	GHJ: IR, adduction, Extension Respiration: "cough muscle"
Pectoralis major	Clavicle (medial half) Sternum Costal cartilages 1-6 Rectus sheath (anterior layer)	Humerus (crest of greater tubercle)	Lateral pectoral n. Medial pectoral n. C5 - T1	Entire muscle: Adduction, IR Clavicular & Sternocostal parts: Flexion, Aids in respiration when shoulder is fixed
Subscapularis	Subscapular fossa	Lesser tubercle of Humerus	Upper Subscapular n. Lower Subscapular n. C5 - C6	GHJ: IR, Stabilization
Teres major	Inferior angle of Scapula	Crest of lesser tubercle of humerus	Thoracodorsal n. C5 - C6	GHJ: IR, Adduction, Extension